Chlamydia

This is a bacterial infection which infects the cervix and can spread to the urethra, fallopian tubes and ovaries in women. It's one of the fastest-spreading STDs and can cause infertility, cervical infections and PID (Pelvic Inflammatory Disease).

Treatable with antibiotics but both you and your partner need treatment before resuming sex.

Genital Warts

There are more than 100 types of human papilloma virus (HPV), basically bumps round the genital area or rectum. It spreads through skin-to-skin contact and there's no cure for the infection, although the warts can be destroyed.

Certain types of HPV can lead to cervical, penile, anal and rectal cancers.

Gonorrhea (The Clap)

A bacterial infection that can lead to infertility, arthritis, heart problems and PID. It's also easier for HIV to infect people with gonorrhea.

A short antibiotic course will cure it but both partners must be treated, even if one doesn't have symptoms. You must also avoid sexual contact until you're cured.

Herpes

There are lots of different types but the main strains involve sores on the mouth or genital areas. Infection occurs when touching the infected area.

There is no cure, although it can be controlled by antiviral drugs which lessen the symptoms and regularity of an attack.